Boerboels, also known as South African Mastiffs, literally translate as “farmer’s dog” and their fiercely territorial nature means they are perfectly suited to guarding homesteads.

Danny Gibson, 50, and wife Paula, 50, of Washington state, USA, are the team behind Barbarian Boerboels – and say their dogs are “the real-life dogs of war”.

Paula said: “Boerboels history states their ancestors fought in war with a Germanic king, so they are literally dogs of war.

“The story goes that an Albanian king sent a boerboel ancestor to Alexander the Great for hunting. He took them hunting for wild boar and deer. When the dog showed no interest Alexander was disappointed and destroyed the dog.

“The Albanian King heard and sent a replacement with the instructions not to waste the dogs time on such minor animals but to give him a lion or elephant to hunt - which Alexander did and was impressed when the dog broke the lions back.

“They're like gladiators, they are at combat all the time, they act like they're always at war with each other.”

Paula and Danny have 14 boerboels, the largest of which is the male Gotti – named after the famous Italian-American gangster who ran the Gambino crime family – who weighs in at over 200lbs.

However, hot on his heels is Fury, who is already 175lbs – the same weight as the largest female in the Barbarian Boerboels kennel, Boudicca – despite being only 13 months old.

Danny said: “He’s going to be one of our up-and-coming studs, he’s starting to become one of my new favorites around here. He’s still got some growing to do, he’s probably going to be over 200 pounds.”

The size of the dogs has led some to assume they must be giving the dogs steroids or feeding them supplements, but Paula stresses that the dogs diet is intentionally kept simple – although the dogs’ appetites means they spend an incredible $18,000 per year on food.

Paula said: “We have a lot of breeders that contact me and say ‘what are you feeding your dog?’ They think that we are feeding it something that's causing its muscles to be big – but we just feed them kibble!”

The registered puppies sell for $2,500 or $3200 if breeding rights are included, and the Barbarian Boerboels team aim for around six litters each year.

The couple first encountered the breed when Paula on the lookout for a large protection dog to keep her safe when out walking.

Paula added: “When I started looking at boerboels, I was a little bit intimidated at first, but decided to go ahead and get one.

“We started looking for a breeder and they were very hard to find at that point, they weren't that popular.

“No one really knew what they were. They were considered a rare breed but we were lucky enough to find one. And that was our first boerboel was Kimora, and we just fell in love with her.”

However there first big hit was a dog named Konan , who garnered a lot of attention in the boerboel world.

Paula said: “We started showing him and advertising him, we got a lot of attention, people wanting puppies. He sadly passed, but all of his puppies carry that thick look, his muscularity and big head.”

Danny and Paula have been breeding dogs for seven years now – with Danny taking on the role of ‘pack leader’ and Paula looking after marketing and merchandise and making custom collars.

And while their dogs might look ferocious, the couple stress that their dogs are above all valued for their temperament.

“They say a dog is man's best friend and a boerboel sticks to his owner like Velcro,” Danny said.

“I personally like that. I like for him to greet me whenever I come home. And if you don't like that, then a boerboel is probably not the dog for you.”

Paula added: “The boerboels are very clingy so there’s no such thing as personal space. If I go to the bathroom, they’re following me to the bathroom. If I don’t close the door, they shove their way through and they sit there while you go!”

“They also do a kind of patrol. If I hear something going on outside and I want to know what's happening, I just say, ‘What’s that?’ and Kimora will charge to the door. I let her out. And she will just start looking around like trying to figure out what's going on, running around the yard really fast.

“Boerboels are excellent home guard dogs and protectors because they're very, very alert. They notice every single thing, if something's out of its usual spot. If someone's in the driveway, they have really good hearing. And they have very good noses. So sometimes they can smell something before they can even see it.

“They're very loving with the family, so they're a great dog to have in the house, but they turn into a fierce protector in 60 seconds if something happens and they're very intimidating.

“I don't see anyone who wanting to take that challenge. So I feel very safe when Danny is away.”